You can map Revit fill patterns to specific hatch patterns in DGN.
On the Patterns tab of the Modify DGN Export Setup dialog (see Export to DGN), you can map Revit fill patterns to specific hatch patterns in DGN as needed.
(Modify Export Setup), select a file in the Load Patterns dialog, and click OK.) You can click Reset All to change all the pattern values in the table back to {Automatically generate pattern}. Alternatively, you can multi-select rows and click {Automatically generate pattern}.
At the bottom of the tab, under Pattern Type, you can specify which type of fill patterns (drafting or model) are listed in the table. The available pattern options are the same, regardless of which pattern type is selected.